Of the various ionic channels, the sodium channel is the best studied, and about which most is known. Not only are its biophysical properties extensively characterized, its biochemical properties have also been intensively investigated in recent years. Now, the primary sequence of amino acids of the channel has been deduced from nucleotide sequence of cloned complementary DNA. This major accomplishment opens a new era of studying such channels by providing the structural basis of their functions in ligand-or toxin-binding, ion-selectivity, and gating of permeability to small ions. Advances in the biochemical studies of the sodium channel have been possible largely because of the unique actions of tetrodotoxin and saxitoxin in selectively binding to a receptor site very close to the outside orifice of the channel. Although these toxins are two of the most important and widely used neurobiological tools, their chemical properties are poorly understood, and the mechanism of their actions is virtually unknown. Similarly, although the functional properties of the sodium channel have been extensively described, the detailed molecular mechanisms of its functions remain as important unresolved problems in biology today. A proposal is hereby submitted seeking partial support for a multidisciplinary conference, the aims of which are: (a) to assess the current state of knowledge on the sodium channel with an integrated approach; (b) to clarify directions for future studies; and (c) to provide models for studies on other ionic channels. The conference is unique in the depth and breadth of coverage contemplated, which are unmatched by any other conference of a similar nature. The conference is likely to have a major impact in this area of studies, because knowledge on the sodium channel serves as a model for studies on other ionic channels, and because the publication of the proceedings of the conference in the Annals of the New York Academy of Sciences will result in wide circulation.